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Message-Id: <1444822919-14650-1-git-send-email-prarit@redhat.com>
Date: Wed, 14 Oct 2015 07:41:59 -0400
From: Prarit Bhargava <prarit@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Prarit Bhargava <prarit@...hat.com>,
Kristen Carlson Accardi <kristen@...ux.intel.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
linux-pm@...r.kernel.org, Doug Smythies <dsmythies@...us.net>
Subject: [PATCH] cpufreq, intel_pstate, Fix intel_pstate powersave min_perf_pct value
On systems that initialize the intel_pstate driver with the performance
governor, and then switch to the powersave governor will not transition to
lower cpu frequencies until /sys/devices/system/cpu/intel_pstate/min_perf_pct
is set to a low value.
The behavior of governor switching changed after commit a04759924e25
("[cpufreq] intel_pstate: honor user space min_perf_pct override on
resume"). The commit introduced tracking of performance percentage
changes via sysfs in order to restore userspace changes during
suspend/resume. The problem occurs because the global values of the newly
introduced max_sysfs_pct and min_sysfs_pct are not lowered on the governor
change and this causes the powersave governor to inherit the performance
governor's settings.
A simple change would have been to reset max_sysfs_pct to 100 and
min_sysfs_pct to 0 on a governor change, which fixes the problem with
governor switching. However, since we cannot break userspace[1] the fix
is now to give each governor its own limits storage area so that governor
specific changes are tracked.
I successfully tested this by booting with both the performance governor
and the powersave governor by default, and switching between the two
governors (while monitoring /sys/devices/system/cpu/intel_pstate/ values,
and looking at the output of cpupower frequency-info). Suspend/Resume
testing was performed by Doug Smythies.
[1] Systems which suspend/resume using the unmaintained pm-utils package
will always transition to the performance governor before the suspend and
after the resume. This means a system using the powersave governor will
go from powersave to performance, then suspend/resume, performance to
powersave. The simple change during governor changes would have been
overwritten when the governor changed before and after the suspend/resume.
I have submitted https://bugzilla.redhat.com/show_bug.cgi?id=1271225
against Fedora to remove the 94cpufreq file that causes the problem. It
should be noted that pm-utils is obsoleted with newer versions of systemd.
Cc: Kristen Carlson Accardi <kristen@...ux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Viresh Kumar <viresh.kumar@...aro.org>
Cc: linux-pm@...r.kernel.org
Cc: Doug Smythies <dsmythies@...us.net>
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
---
drivers/cpufreq/intel_pstate.c | 120 +++++++++++++++++++++++++---------------
1 file changed, 75 insertions(+), 45 deletions(-)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 3af9dd7..78b4be5 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -156,7 +156,20 @@ struct perf_limits {
int min_sysfs_pct;
};
-static struct perf_limits limits = {
+static struct perf_limits performance_limits = {
+ .no_turbo = 0,
+ .turbo_disabled = 0,
+ .max_perf_pct = 100,
+ .max_perf = int_tofp(1),
+ .min_perf_pct = 100,
+ .min_perf = int_tofp(1),
+ .max_policy_pct = 100,
+ .max_sysfs_pct = 100,
+ .min_policy_pct = 0,
+ .min_sysfs_pct = 0,
+};
+
+static struct perf_limits powersave_limits = {
.no_turbo = 0,
.turbo_disabled = 0,
.max_perf_pct = 100,
@@ -169,6 +182,12 @@ static struct perf_limits limits = {
.min_sysfs_pct = 0,
};
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE
+static struct perf_limits *limits = &performance_limits;
+#else
+static struct perf_limits *limits = &powersave_limits;
+#endif
+
static inline void pid_reset(struct _pid *pid, int setpoint, int busy,
int deadband, int integral) {
pid->setpoint = setpoint;
@@ -255,7 +274,7 @@ static inline void update_turbo_state(void)
cpu = all_cpu_data[0];
rdmsrl(MSR_IA32_MISC_ENABLE, misc_en);
- limits.turbo_disabled =
+ limits->turbo_disabled =
(misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE ||
cpu->pstate.max_pstate == cpu->pstate.turbo_pstate);
}
@@ -274,14 +293,14 @@ static void intel_pstate_hwp_set(void)
for_each_online_cpu(cpu) {
rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value);
- adj_range = limits.min_perf_pct * range / 100;
+ adj_range = limits->min_perf_pct * range / 100;
min = hw_min + adj_range;
value &= ~HWP_MIN_PERF(~0L);
value |= HWP_MIN_PERF(min);
- adj_range = limits.max_perf_pct * range / 100;
+ adj_range = limits->max_perf_pct * range / 100;
max = hw_min + adj_range;
- if (limits.no_turbo) {
+ if (limits->no_turbo) {
hw_max = HWP_GUARANTEED_PERF(cap);
if (hw_max < max)
max = hw_max;
@@ -350,7 +369,7 @@ static void __init intel_pstate_debug_expose_params(void)
static ssize_t show_##file_name \
(struct kobject *kobj, struct attribute *attr, char *buf) \
{ \
- return sprintf(buf, "%u\n", limits.object); \
+ return sprintf(buf, "%u\n", limits->object); \
}
static ssize_t show_turbo_pct(struct kobject *kobj,
@@ -386,10 +405,10 @@ static ssize_t show_no_turbo(struct kobject *kobj,
ssize_t ret;
update_turbo_state();
- if (limits.turbo_disabled)
- ret = sprintf(buf, "%u\n", limits.turbo_disabled);
+ if (limits->turbo_disabled)
+ ret = sprintf(buf, "%u\n", limits->turbo_disabled);
else
- ret = sprintf(buf, "%u\n", limits.no_turbo);
+ ret = sprintf(buf, "%u\n", limits->no_turbo);
return ret;
}
@@ -405,12 +424,12 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b,
return -EINVAL;
update_turbo_state();
- if (limits.turbo_disabled) {
+ if (limits->turbo_disabled) {
pr_warn("intel_pstate: Turbo disabled by BIOS or unavailable on processor\n");
return -EPERM;
}
- limits.no_turbo = clamp_t(int, input, 0, 1);
+ limits->no_turbo = clamp_t(int, input, 0, 1);
if (hwp_active)
intel_pstate_hwp_set();
@@ -428,11 +447,15 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b,
if (ret != 1)
return -EINVAL;
- limits.max_sysfs_pct = clamp_t(int, input, 0 , 100);
- limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
- limits.max_perf_pct = max(limits.min_policy_pct, limits.max_perf_pct);
- limits.max_perf_pct = max(limits.min_perf_pct, limits.max_perf_pct);
- limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
+ limits->max_sysfs_pct = clamp_t(int, input, 0 , 100);
+ limits->max_perf_pct = min(limits->max_policy_pct,
+ limits->max_sysfs_pct);
+ limits->max_perf_pct = max(limits->min_policy_pct,
+ limits->max_perf_pct);
+ limits->max_perf_pct = max(limits->min_perf_pct,
+ limits->max_perf_pct);
+ limits->max_perf = div_fp(int_tofp(limits->max_perf_pct),
+ int_tofp(100));
if (hwp_active)
intel_pstate_hwp_set();
@@ -449,11 +472,15 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
if (ret != 1)
return -EINVAL;
- limits.min_sysfs_pct = clamp_t(int, input, 0 , 100);
- limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct);
- limits.min_perf_pct = min(limits.max_policy_pct, limits.min_perf_pct);
- limits.min_perf_pct = min(limits.max_perf_pct, limits.min_perf_pct);
- limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
+ limits->min_sysfs_pct = clamp_t(int, input, 0 , 100);
+ limits->min_perf_pct = max(limits->min_policy_pct,
+ limits->min_sysfs_pct);
+ limits->min_perf_pct = min(limits->max_policy_pct,
+ limits->min_perf_pct);
+ limits->min_perf_pct = min(limits->max_perf_pct,
+ limits->min_perf_pct);
+ limits->min_perf = div_fp(int_tofp(limits->min_perf_pct),
+ int_tofp(100));
if (hwp_active)
intel_pstate_hwp_set();
@@ -533,7 +560,7 @@ static void byt_set_pstate(struct cpudata *cpudata, int pstate)
u32 vid;
val = (u64)pstate << 8;
- if (limits.no_turbo && !limits.turbo_disabled)
+ if (limits->no_turbo && !limits->turbo_disabled)
val |= (u64)1 << 32;
vid_fp = cpudata->vid.min + mul_fp(
@@ -622,7 +649,7 @@ static void core_set_pstate(struct cpudata *cpudata, int pstate)
u64 val;
val = (u64)pstate << 8;
- if (limits.no_turbo && !limits.turbo_disabled)
+ if (limits->no_turbo && !limits->turbo_disabled)
val |= (u64)1 << 32;
wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
@@ -702,7 +729,7 @@ static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
int max_perf_adj;
int min_perf;
- if (limits.no_turbo || limits.turbo_disabled)
+ if (limits->no_turbo || limits->turbo_disabled)
max_perf = cpu->pstate.max_pstate;
/*
@@ -710,11 +737,11 @@ static void intel_pstate_get_min_max(struct cpudata *cpu, int *min, int *max)
* policy, or by cpu specific default values determined through
* experimentation.
*/
- max_perf_adj = fp_toint(mul_fp(int_tofp(max_perf), limits.max_perf));
+ max_perf_adj = fp_toint(mul_fp(int_tofp(max_perf), limits->max_perf));
*max = clamp_t(int, max_perf_adj,
cpu->pstate.min_pstate, cpu->pstate.turbo_pstate);
- min_perf = fp_toint(mul_fp(int_tofp(max_perf), limits.min_perf));
+ min_perf = fp_toint(mul_fp(int_tofp(max_perf), limits->min_perf));
*min = clamp_t(int, min_perf, cpu->pstate.min_pstate, max_perf);
}
@@ -988,32 +1015,35 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
if (policy->policy == CPUFREQ_POLICY_PERFORMANCE &&
policy->max >= policy->cpuinfo.max_freq) {
- limits.min_policy_pct = 100;
- limits.min_perf_pct = 100;
- limits.min_perf = int_tofp(1);
- limits.max_policy_pct = 100;
- limits.max_perf_pct = 100;
- limits.max_perf = int_tofp(1);
- limits.no_turbo = 0;
+ pr_debug("intel_pstate: set performance\n");
+ limits = &performance_limits;
return 0;
}
- limits.min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
- limits.min_policy_pct = clamp_t(int, limits.min_policy_pct, 0 , 100);
- limits.max_policy_pct = (policy->max * 100) / policy->cpuinfo.max_freq;
- limits.max_policy_pct = clamp_t(int, limits.max_policy_pct, 0 , 100);
+ pr_debug("intel_pstate: set powersave\n");
+ limits = &powersave_limits;
+ limits->min_policy_pct = (policy->min * 100) / policy->cpuinfo.max_freq;
+ limits->min_policy_pct = clamp_t(int, limits->min_policy_pct, 0 , 100);
+ limits->max_policy_pct = (policy->max * 100) / policy->cpuinfo.max_freq;
+ limits->max_policy_pct = clamp_t(int, limits->max_policy_pct, 0 , 100);
/* Normalize user input to [min_policy_pct, max_policy_pct] */
- limits.min_perf_pct = max(limits.min_policy_pct, limits.min_sysfs_pct);
- limits.min_perf_pct = min(limits.max_policy_pct, limits.min_perf_pct);
- limits.max_perf_pct = min(limits.max_policy_pct, limits.max_sysfs_pct);
- limits.max_perf_pct = max(limits.min_policy_pct, limits.max_perf_pct);
+ limits->min_perf_pct = max(limits->min_policy_pct,
+ limits->min_sysfs_pct);
+ limits->min_perf_pct = min(limits->max_policy_pct,
+ limits->min_perf_pct);
+ limits->max_perf_pct = min(limits->max_policy_pct,
+ limits->max_sysfs_pct);
+ limits->max_perf_pct = max(limits->min_policy_pct,
+ limits->max_perf_pct);
/* Make sure min_perf_pct <= max_perf_pct */
- limits.min_perf_pct = min(limits.max_perf_pct, limits.min_perf_pct);
+ limits->min_perf_pct = min(limits->max_perf_pct, limits->min_perf_pct);
- limits.min_perf = div_fp(int_tofp(limits.min_perf_pct), int_tofp(100));
- limits.max_perf = div_fp(int_tofp(limits.max_perf_pct), int_tofp(100));
+ limits->min_perf = div_fp(int_tofp(limits->min_perf_pct),
+ int_tofp(100));
+ limits->max_perf = div_fp(int_tofp(limits->max_perf_pct),
+ int_tofp(100));
if (hwp_active)
intel_pstate_hwp_set();
@@ -1057,7 +1087,7 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
cpu = all_cpu_data[policy->cpu];
- if (limits.min_perf_pct == 100 && limits.max_perf_pct == 100)
+ if (limits->min_perf_pct == 100 && limits->max_perf_pct == 100)
policy->policy = CPUFREQ_POLICY_PERFORMANCE;
else
policy->policy = CPUFREQ_POLICY_POWERSAVE;
--
1.7.9.3
--
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